Radiation system with several radiation sources directed to a control point

ABSTRACT

The radiation system has several radiation sources aimed toward a central point. These radiation sources are on arc element that pivots on an axis. The center can hence be irradiated from different sides. The radiation sources preferably have irregularly adjustable diaphragms. The system is suitable for irradiating any part of the human body. It is easy to manufacture and simple to used.

The invention concerns a radiation system with several radiation sourcesaimed at a central point. Such a radiation system is known by the nameof a “gamma knife”. This system is a radioisotope irradiation systemwith 201 cobalt sources. These cobalt sources are on the lateral surfaceof a hollow sphere an all point toward a center. This system is highlysuitable for irradiating the human head positioned inside the hollowsphere. This device cannot be used to irradiate the rest of the body,however. In addition, the gamma knife is relatively expensive tomanufacture, and servicing an operation are costly and time-consuming.Only a limited degree of fractionated irradiation can be done with thegamma knife.

Stereotactic linear accelerators represent another prior-art irradiationsystem. These systems must be carefully adjusted before use inradiosurgery, and the adjustment must be continuously monitored. Theresulting involved quality assurance makes it difficult to use thesystem in small institutions and hospitals. In addition, the operationand service costs are high for linear accelerators. Furthermore, theradiation time is relatively long due to the sequential processing ofthe individual radiation fields.

The invention is based on the problem of offering an irradiation systemthat can be used for the entire body.

This problem is solved by placing the radiation source on an arc elementthat pivots on a first axis, and the arc element and a patient tablerotate relative to each other on a second axis perpendicular to thefirst axis.

The use of a pivotable arc element allows a point or area to beirradiated from several sides using fewer radiation sources. Inaddition, the selected distance of the radiation sources to the humanbody can be such that the body is placed under the arch or in the arc.Since only one arc element has to be moved on a fixed axis, a highdegree of mechanical precision can be attained using simple means.

The device according to the invention provides that all radiationsources are directed toward a central point. The arc is also able torotate relative to the patient table on an axis perpendicular to theswivel axis of the arc. This makes it possible to irradiate the centralpoint from different sides with a radiator and radiate the center fromradically different angles with the same or different radiators whilemoving the device on the two described axes.

The entire system can be easily constructed, and its easy operationallows it to be used in less developed countries.

It is advantageous when the arc element describes an arc of less than ca270° and preferably ca 180°. There remains enough room under the arcelement to securely place a patient table.

It is particularly advantageous when the axis on which the arc elementpivots runs through the central point at which the radiation sources areaimed. This allows a point to be irradiated from several sides when thearc element is pivoted.

In one advantageous embodiment of the radiation system, the axis is ahollow shaft. Since this allows a view through the shaft, it is easierto position the irradiated body under the arc element. If thepositioning is automatic, a laser or other measuring devices or animaging system can be located in the hollow shaft.

It is advantageous when each radiation source has a diaphragm. Dependingon the use, the diaphragms can be adjusted the same or differently fromradiation source to radiation source.

A particularly advantageous diaphragm can be irregularly adjusted sincesuch a diaphragm can be optimally adapted to the area to be irradiated.The setting of the diaphragm can also be varied while the arc element ismoved so that a different diaphragm setting can selected depending onthe direction of the radiation.

To securely position the patient, it is suggested that the radiationsystem have a table that can be positioned relative to the arc element.Such a table is preferably adjustable in the x, y and z axes so that thecenter of the radiation sources can be aligned with the body part to beirradiated by moving the table while the arc element remains stationary.

The table can be advantageously rotated around an axis that intersectsthe center and is perpendicular to the surface on which the patientrests. If the table e.g. is rotatable on a y-axis, the arc element canbe swung on any axis lying in the x-z plane. In addition, rotating thehuman body on the y-axis allows the central point at which the radiationsources are aimed to be irradiated from different sides.

A simple radiation system design has 5-10 radiators. This corresponds toan angle between the radiators of 20°-30° if the radiators are on asemicircular arc element. The use of fewer radiators lowers the cost ofeach radiation source.

Given the relatively high costs of individual radiation sources anddiaphragms, it can be advantageous when at least one radiation source ismoveably mounted on the arc element. All radiation sources may bemounted on the arc element so that they can shift a certain angle.

To easily irradiate a human body, it is suggested that the angle betweenthe radiation sources and the center be ca 1 m. The arc then has anopening of ca 2 m in which the patient can be placed.

In one advantageous embodiment of the radiation source, the radiatorsare designed as containers that allow the radiation source to be moved.The radiation sources therefore do not have to be changed locally. It isvery dangerous for the operating personnel to change conventionalradiators, and it is expensive since only specialists can change them.The radiators according to the invention designed as containers can e.g.be screwed via a thread into the arc element and can be screwed out ofthe arc element and exchanged after the radiation source fails. The usedradiators are returned to the radiator manufacturer together with thecontainers, and a new radiator container is screwed into the arc inplace of the original radiation container. They are therefore exchangedquickly and safely, and this can be done in less developed nations aswell.

The design of the radiators as transportable containers can also be usedfor other radiation devices independent of the described radiationsystem.

A preferred exemplary embodiment of the invention is shown in thedrawing and will be explained in the following.

Shown are:

FIG. 1 A three-dimensional representation of a radiation system with apatient resting surface in a first position, and

FIG. 2 A three-dimensional representation of a radiation system with apatient resting surface in a second position.

The radiation system in FIG. 1 essentially consists of a gate-shapedradiation part 1 and a table 2 underneath with a patient resting surface3.

The gate-shaped radiation part 1 has two spaced stands 4 and 5 whose topends 6, 7 are connected by an arc element 8. The arc element 8 isattached at the top ends 6 and 7 by two bearings 9 and 10. Thesebearings 9 and 10 allow the arc element 8 to pivot on a line thatconnects the bearings and forms the pivot axis 11.

Seven essentially semicircular cobalt 60 radiators are in the arcelement 8. These radiation sources 12-18 are aimed toward a center 19,and the angle 20 between two neighboring radiation sources 15, 16 is ca25°.

Each radiation source 12-18 has a diaphragm 21 that is schematicallyrepresented in the figure and can be irregularly adjusted.

Under the arc 8, the patient resting surface 3 can be positions so thatthe intersection 19 of the radiation sources 12-18 lie on a specificpoint 19 in the body of a person 21 lying on the patient table 3. Thepatient resting surface 3 is therefore part of the table 2 that allowsthe patient resting surface to be precisely positioned in space. Inaddition, the patient resting surface 3 can be rotated on aperpendicular y-axis 22 that intersects the center 19.

When the described radiation system is used, a patient 21 is fistpositioned on the patient resting surface 3 so that the connecting axis11 between the bearings 9 and 10 intersect the body part to be radiated.The bearings 9 and 10 are designed as hollow shafts so that you can lookthrough them to properly position the patient. Alternately, a laser beamcan be in the hollow shafts of the bearings 9 and 10 to position thepatient.

After the patient is positioned, the radiation sources 12-18 areactivated, and the arc element 8 is pivoted slowly on the pivot axis 11by a drive 23 (FIG. 2). The diaphragms 21 of the radiation sources 12-18can be in a fixed position, or their position can be changed while thearc element 8 is pivoted. The precise setting of the diaphragms 21 isdetermined by the shape of the body part to be irradiated. Varying thediaphragm 21 during the pivoting process of the arc element 8 allowsoptimum radiation that is preferably calculated with a computer.

In addition or alternately to pivoting the arc element 8, the patientresting surface 3 is pivoted on the vertical y-axis 22. This also allowsthe center 19 to be irradiated from different sides.

While the FIG. 1 describes irradiating a central point 19 in the chestarea of a patient 21, FIG. 2 shows a patient 21 being irradiated in theprostate area. The design of the device in FIG. 2 corresponds to thedesign in FIG. 1.

What is claimed is:
 1. A radiation system comprising: (a) one or moreradiation sources mounted on an arc element and aimed toward a centralpoint, wherein the arc element is arranged to pivot about a first axis;(b) a table arranged to rotate on a second axis perpendicular to thefirst axis.
 2. The radiation system of claim 1 wherein the arc elementcovers an arc of less than about 270°.
 3. A The radiation system ofclaim 1 wherein the arc element covers an arc of about 180°.
 4. Theradiation system of claim 1 wherein at least one of the first and secondaxes intersects the central point.
 5. The radiation system of claim 1wherein the first and second axes intersect the central point.
 6. Theradiation system of claim 1 wherein the arc element comprises a hollowshaft along the first axis.
 7. The radiation system of claim 1 whereineach radiation source comprises a diaphragm arranged to controlradiation exiting the radiation source.
 8. The radiation system of claim7 wherein each radiation diaphragm is individually adjustable.
 9. Theradiation system of claim 1 wherein the table can be three dimensionallypositioned relative to the arc element.
 10. The radiation system ofclaim 1 comprising from 5 to 10 radiation sources.
 11. The radiationsystem of claim 1 wherein at least one of the one or more radiationsources is moveably mounted on the arc element.
 12. The radiation systemof claim 1 wherein the radiation sources are positioned at a distancefrom the center of from about 1 to about 2 m.
 13. The radiation systemof claim 1 wherein the radiation sources are designed as transportablecontainers.